title: From 'omics to otoliths: responses of an estuarine fish to endocrine disrupting compounds across biological scales.
abstract: Endocrine disrupting chemicals (EDCs) cause physiological abnormalities and population decline in fishes. However, few studies have linked environmental EDC exposures with responses at multiple tiers of the biological hierarchy, including population-level effects. To this end, we undertook a four-tiered investigation in the impacted San Francisco Bay estuary with the Mississippi silverside (Menidia audens), a small pelagic fish. This approach demonstrated links between different EDC sources and fish responses at different levels of biological organization. First we determined that water from a study site primarily impacted by ranch run-off had only estrogenic activity in vitro, while water sampled from a site receiving a combination of urban, limited ranch run-off, and treated wastewater effluent had both estrogenic and androgenic activity. Secondly, at the molecular level we found that fish had higher mRNA levels for estrogen-responsive genes at the site where only estrogenic activity was detected but relatively lower expression levels where both estrogenic and androgenic EDCs were detected. Thirdly, at the organism level, males at the site exposed to both estrogens and androgens had significantly lower mean gonadal somatic indices, significantly higher incidence of severe testicular necrosis and altered somatic growth relative to the site where only estrogens were detected. Finally, at the population level, the sex ratio was significantly skewed towards males at the site with measured androgenic and estrogenic activity. Our results suggest that mixtures of androgenic and estrogenic EDCs have antagonistic and potentially additive effects depending on the biological scale being assessed, and that mixtures containing androgens and estrogens may produce unexpected effects. In summary, evaluating EDC response at multiple tiers is necessary to determine the source of disruption (lowest scale, i.e. cell line) and what the ecological impact will be (largest scale, i.e. sex ratio).
authors.affiliation: Bodega Marine Laboratory, University of California Davis, Bodega Bay, California, United States of America ; Department of Environmental Toxicology, University of California Davis, Davis, California, United States of America ; Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, North Carolina, United States of America.
authors.forename: Susanne M
authors.initials: SM
authors.lastname: Brander
authors.forename: Richard E
authors.initials: RE
authors.lastname: Connon
authors.forename: Guochun
authors.initials: G
authors.lastname: He
authors.forename: James A
authors.initials: JA
authors.lastname: Hobbs
authors.forename: Kelly L
authors.initials: KL
authors.lastname: Smalling
authors.forename: Swee J
authors.initials: SJ
authors.lastname: Teh
authors.forename: J Wilson
authors.initials: JW
authors.lastname: White
authors.forename: Inge
authors.initials: I
authors.lastname: Werner
authors.forename: Michael S
authors.initials: MS
authors.lastname: Denison
authors.forename: Gary N
authors.initials: GN
authors.lastname: Cherr
mesh_terms: D000818:Animals; D001483:Base Sequence; D049628:Body Size; D017931:DNA Primers; D052244:Endocrine Disruptors / Q000633:toxicity*; D063366:Estuaries; D005260:Female; D005399:Fishes; D015870:Gene Expression; D008297:Male; D060888:Real-Time Polymerase Chain Reaction; D012744:Sex Ratio
chemical_list: D017931:DNA Primers; D052244:Endocrine Disruptors